Tapered vs straight head tube / fork


Just wondering, anyone feeling difference between the two on road bikes, performance wise?

On my two bikes, both head tubes are straight, but one has aluminum fork tube and another one is carbon. The latter feels a lot more flexy, especially on climbs I feel I need to employ different hands position to put down power into pedals and not the flex (hands closer to the stem kinda help, but not too comfortable).

When I say flexy, I mean I can rock the handlebars up and down probably +/-1cm or more while standing, it always bothered me. Flex appears to originate somewhere at the fork crown and where fork split.

The front flexy bike is Felt AR, older model with the curved downtube (2013 and older).

On straights and cruising speeds the AR excels.

Does the tapered headtube stiffen up the bike and if so, do you see the benefit of stiffer front end?


Are you sure your headset isn’t loose?

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Good point, but no, bike is very tight all round. I can also turn handlebars a good bit while on trainer and and front wheel being locked on the raiser and my weight. It is twisting in all directions same amount kinda, up and down, right and left.

I have maybe 5 or 6 different stems and handlebars and it is worse with wider bars, say 44, now riding 40.

It never gave me a trouble, but I never felt secure on high speed downhills. But I notice it doesn’t climb as well as the other bike.

There can be a lot more differences at work here, other than taper vs non-taper. Are you using the same stem and bars (or very similar ones) between the 2 bikes? Do you have a similar distance between the top headset bearing and the stem? Is the distance between the top and bottom headset bearings similar?

A noodle fork tube combined with a short bearing span and a long entension above the top bearing will feel even more noodle-y. Add a long stem, and you’re steering through molasses.

Thanks. They are very different geometry, material and size bikes. The alu one has alloy steerer carbon fork, while Felt has all carbon fork. They are setup to be a close match fit wise at an expense of different stems and stuff because I use one for training and another for racing. I know I probably won’t resolve it, it is just how Felt designed it, I suppose to be aero, but flexy.

What I really wanted to hear is experience from people, whether stiff frontend has benefits performance wise or noodle’ish one is as good, or better. Just if I decide to go for another bike some day. We all know stiffness is not always the key to speed.

Mechanically-speaking, the stiffness from the frame to the bars can be quite different from that from the frame to the front hub; this is particularly true if the fork is stiff, but the fork tube isn’t, and even more as overhangs get added (long distance from top bearing to stem, long stem). But while a “compliant” front-end can feel more comfortable, it comes with a loss of steering control, and power loss in sprints.

So performance-wise: if you’re into long rides on flat terrain, noodle is probably ok; if you’re into alpine descents at the edge of skidding down into an abyss or Cavendish-style sprint finishes, not so much.

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Thanks for that. I agree. Felt doesn’t sprint well. In fact I afraid to sprint on it, it doesn’t inspire confidence that something will not snap. Yet, in 5 years it never let me down in any way, in fact the alu stiffer bike crashed twice due to front skidding, but again, it could be down to other things, like tyres.